Ms Dwan said Stasauskas joined the fray after his mate was shoved by an unknown male.

Police prosecutor Sergeant Jo Colston said Stasauskas, held the unknown man down and punched him numerous times in the head.

The fight, which was captured on CCTV, continued for about 30 seconds until McDonald's staff stepped in to break it up. All those involved in the fray left the restaurant as staff phoned police. The incident took place about 2.30am on May 23.

Ms Dwan said Stasauskas was a self-employed sign installer who had previously completed an apprenticeship as a butcher.

She said her client had no criminal history.

Ms Dwan said the 21-year-old was remorseful that he had got involved in the fight instead of walking away and that his behaviour that morning was "out of character".

Magistrate Roger Stark told Stasauskas he should be ashamed of his behaviour.

"You held someone down and punched him to the head.

"You are fortunate you didn't cause him any serious injury otherwise you could have had a complaint made against you and found yourself charged with a more serious offence."

Stasauskas was convicted and fined $500. No convictions were recorded.